1. Field of the Invention
This invention relates to manufacturing methods for metal design panels made by complex molding using surface decorative metal members and thermoplastic resins.
2. Description of the Related Art
Metal design panels are manufactured by processing metal plate panels serving as surface decorative members, and they have been adapted to a variety of fields such as faceplates, nameplates, building materials for interiors and exteriors, and automobile decorating members for interiors and exteriors. A first example of a conventionally-known manufacturing method of a metal design panel will be described with reference to FIGS. 15A to 15C.
In a first step, there is provided in advance a solid member 100 shown in FIG. 15A, which is made by integral formation using a thermoplastic resin. A curved hollow 101 is formed on the surface of the solid member 100; and legs 102 are formed in the backside of the solid member 100. In a second step, there is provided a metal plate panel 103 serving as a surface decorative member, wherein the metal plate panel 103 is slightly bent in advance to match the curved hollow 101 and is then arranged on the surface of the solid member 100 by use of adhesive (see FIG. 15B). In a third step, ends of the metal plate panel 103, which are extended downwardly from both sides of the solid member 100, are bent upon press working so that both ends of the solid member 100 are covered with bent portions of the metal plate panel 103; thus, it is possible to completely produce a metal design panel as shown in FIG. 15C.
In a second example of the conventionally-known manufacturing method, the metal plate panel 103 is formed in advance in a prescribed shape as shown in FIG. 15C, wherein primer is coated onto the backside of the metal plate member 103 in order to improve adhesion, and then, the metal plate panel 103 is arranged in a metal mold of an injection molding machine (not shown); thereafter, insert molding for filling the metal mold with a thermoplastic resin is performed to form the solid member 100.
In the first example of the manufacturing method described above, it is necessary to perform preliminary formation of the metal plate panel 103 and press working for bending ends of the metal plate panel 103. In the second example of the manufacturing method, it is necessary to coat primer onto the backside of the metal plate panel 103, which does not rationalize or improve manufacturing.
Even though the metal design panel is produced by the aforementioned manufacturing method, a resin member and a surface decorative metal member (i.e., the solid member 101 and the metal plate panel 103) are easily separated from each other at contact areas therebetween due to differences of materials (i.e., metal and resin) therefor. It is well known that building materials for interiors and exteriors and/or automobile materials for interiors and exteriors are exposed to severe environmental conditions, subjecting them to relatively large temperature changes, and that metal and resin materials differ from each other in expansion coefficients. Therefore, even when adhesive or primer is applied, the surface decorative metal member and the resin member are easily separated from each other at contact areas therebetween. This causes a drawback in that the surface decorative metal member easily floats and moves relative to the resin member, causing abnormal sound (or noise) unexpectedly when vibrated.